This invention relates to a dynamoelectric machine and more particularly to a fractional horsepower induction motor such as may be utilized with an overhead ceiling fan.
Overhead ceiling fan motors are oftentimes multi-pole motors, for example, an 18 pole permanent split capacitor (PSC) motor, which have a relatively slow synchronous speed (e.g., 400 rpm). These motors typically include a stator assembly having a core made of a stack of laminations of suitable ferromagnetic material having a central bore therethrough and having radial slots extending outwardly from the bore for receiving a multiplicity of coils of magnet wire so as to constitute the windings of the motor. A rotor is positioned within the bore of the core of the stator assembly and the rotor includes a hollow rotor shaft extending endwise from the rotor body. The stator further includes end shields or bearing supports carrying suitable bearings, for example ball bearings, which receive and journal the rotor shaft such that the rotor is free to rotate within the bore of the stator. Typically, an overhead ceiling fan motor is suspended from a support pipe which is attached to a suitable structure on the ceiling. The fan blades for the overhead ceiling fan are attached to a hub secured to the end of the rotor shaft which extends down below the motor such that the hub and the blades rotate with the rotor shaft.
Oftentimes a switch housing is provided below the fan blade hub which encloses a control switch for controlling operation of the motor (i.e., energization, de-energization, and speed control of the motor). Additionally, the switch housing may be provided so as to support a lighting fixture in a combination overhead ceiling fan/lighting fixture appliance. With the switch housing located stationarily below the rotating fan blade hub, it is conventional to provide a hollow, stationary wire way extending through the rotor shaft and to provide a passageway for electrical lead wires between the windings of the motor, the speed control and on/off switch located in the switch housing, the light fixture carried by the switch housing, and the source of electrical power which is typically located on the ceiling of the building.
Heretofore, as shown in FIG. 10 of the present drawings, it was conventional in prior art overhead ceiling fans to securely locate the wire way relative to the upper end shield of the motor by means of a locknut located within a hollow hub formed on the end shield. Then, a flanged cap was removably secured to the hub formed on the end shield by a plurality of screws with this flanged hub having a receptacle for threadably receiving the pipe support suspending the overhead ceiling fan from the overhead ceiling structure. However, as shown in FIG. 10, this construction required a multiplicity of additional parts to be attached to the motor and required additional steps in the manufacture of the motor. Still further, such a structure required a considerable increase in materials, costs, and overall length (or height) of the motor for the overhead ceiling fan. It will be appreciated in many applications for overhead ceiling fans in modern day residential dwelling units with 8 foot ceilings, even small increases in the overall length of the overhead ceiling fan is a substantial disadvantage.
In another type of prior art overhead ceiling fan, as illustrated in FIG. 11, a housing structure ws rigidly attached to the stator assembly of the motor so as to extend above the motor and to provide a support for a hub into which the support pipe for the motor is threadably secured. The wire way was fixedly secured relative to the end shields of the motor by press fitting a cup-shaped member into a receptacle formed in the end shield of the motor so as to stationarily affix the wire way relative to the end shield. This arrangement, as shown in FIG. 11, added appreciably to the overall length of the overhead ceiling fan motor, required additional parts, and was expensive to manufacture and assemble.